Credit unions are good and don't ever take a mortgage longer than 15 years. My wife and I paid 10 years on our 30-year mortgage and only got 10-15% of it paid off in principle. We refinanced to a 15 year and will save $100,000 in interest and gain equity very quickly. I wish I would have done that in the first place and I would be free and clear already.
Very rare that a lender will not let you pay down a note faster than scheduled. Doing so reduces the interest paid on the balance while not reducing the payments, effectively doubling the speed of principal pay-down.
